HVLP Paint Spraying

[Leroy]

My cobra is over 10 years old and due a new paint job. I painted the cobra before w/ acrylic lacquer using a normal high pressure gun. This time I would like to use the HVLP type gun, due to less over-spray and less paint, saving money on paint. Planning on using a base coat - clear coat paint. My question is has anyone used this type in painting their car and how different is compared to the old way. Any tricks,etc.
Thank you,
Lee

[BT SNAKE]

Leroy,
I just finished spraying my GT40 with a HVLP Sata gun.
Frankly I see about the same amount of over spray from
it as I do my old Binks 7 gun. The HVLP works really well
and I like the gravity fed cup much better. It seems to have
a better spray adjustment pattern than the Binks. The
best tip I can give you is to keep the gun clean. Any
contamination what so ever will result in disaster. I have
two tips for the gun. A 1.4MM and a 2.2. The 2.2 is mostly
used for heavy primer sealers.
Remember to do all the prep work cause base coat hides
no blimishes. If it ain't right you will see it in the final
product.

Hersh

[Double Venom]

ALL RIGHT HERSCH!

DV

[427sharpe]

I switched over to HVLP about 4 years ago, and it is a much better system. It does not create near the amount of waste as the old system, if you are using the correct pressure. I think you are right on to go to the 2 stage system as well. It will hold up much better. The only tip i give in addition to Hersch is to be sure to wet sand the color coat after it dries to remove ANY imperfection, and you will get awesome results. The OE guys use the 2 stage system to hide their hideous paint jobs...go to just about any mfg and really look at the paint, you'll see runs, orange peel, sags and God knows what else..all hidden by the nice, smooth, tough clear coat to make it all shiny! As far as equipment, I like the Sharp remote gun. Holds up very well, and you dont have to carry the weight of the paint around while working because the reservoir is fed to the gun by a hose about 5' long. Pretty economical price too, for a professional gun (about 25 bucks higher than a Binks #7 here in Dallas).

[Clois Harlan]

I just want to make sure I understand you, did you say to wet sand the "COLOR" coat?
When I painted my Cobra I used an Optima HVLP gravity feed (my old Binks 7 and Develbiss were pretty much shot) and I used Ditzler two stage Paint System . I was told by the Ditzler rep at the time not to touch my color coat because any scratches would show through. I sprayed three good coats of color and waited about two hours and masked off my stripes and shot three more color coats for my stripes. Waited another 2 hours and shot three medium coats of clear on my top coat and then mixed a hot batch of clear and held my gun back about 14 inches to burn everything in since I knew I was going to color sand my finish coat.

I used 3M Gold 1200 grit wet or dry and hot soapy water to color sand my clear coat. Then I buffed everything with the 3M Perfection system. Great finish and I really like the HVLP system although you do still get overspray.

[DAVID GAGNARD]

Clois;

Yes you can wet sand the "color coat". We did in the shop but only when neccessary as when we found "trash" or had a run or sag in the color coat. Same as sanding the clear,but we usually used 1500 or higher number sand paper,sanding very lightly,you do not have to sand the hell out of it like you sometimes do for clear....But as always, check with the paint manufacter for their recomendations for that specific product.....

Hated to have to wet sand the color cause now you usually have to remask evrything as the paper gets all wet and falls apart and you have to make sure it is completely dry before spraying clear,especially under and around moldgings and such. Water droplets have a way of hiding and then when you start spraying clear,they appear from nowhere and make nice little tiny bubbles in your clear....

David

[427sharpe]

Yes, we always wet sand the color coat with 2000 grit paper. Don't go crazy, just remove any imperfections and get the color coat as smooth and as even as possible. The difference between doing this and just spraying over the color coat as is will be amazing..the better you leave the base (color) coat, the more depth and brilliance the final finish will have.

[Bruce Botti]

I would definitely check the manufacturer's P-sheets before color sanding the basecoat. All the PPG BC/CC systems that I use say to never sand the basecoat prior to the clearcoat going on. They say to even be careful when using a tack cloth. Even the slightest sanding scratch will be magnified by the clearcoat. If the basecoat is sanded, it is recommended to hit it with more base prior to the clear.

For great info on painting, go to www.autobodystore.com. It is a great site with many helpful folks....just like this site.

Take care,
Bruce

[sfry]

This could take all day.
Sanding Base: Basecoat/Clearcoat is considered a chemical adhesion process. When you sand the base you have now changed the chemistry to think its a mechnical adhesion. IT wont fly! You will have a basecoat delamination. The reason is that when you apply the base is will go through a process called a polyvinyl resin flotation. This is a seperation between pigment and binder. The pigment is heavier than the binder thus resulting is in a setteling of the pigment at the bottom of the film layer. The binder is the glue that holds the pigment togeather and promotes the adhesion between the base and clear, it raises to the top of the film. THIS IS WHAT YOU SAND OFF. And no it does not replace it when you apply more base. The key to remember is when you have to sand base, keep it to the size of the particulate you are removing. NEVER SAND THE ENTIRE JOB. I have been called to look at more warrantys due to this issue.

I will talk about HVLP Vs Conventional spray equipment in another thread.
G.Shannon Fry

[427sharpe]

Hmmm....delamination?? We always touch sand the color coat before shooting clear on cars meant for show and have NEVER had any adhesion trouble. A lot of show finishes are done this way as well to get maximim depth and brilliance. I guess it would be better just to spray a perfect color coat first though!